What actually slows a computer down, and what you can fix
A slow computer usually comes from one of four things: too many programs running at once, a hard drive that is nearly full, malware or unwanted software eating resources, or a hard drive that is failing. You can fix the first three yourself in an hour or less. The fourth requires replacing the drive.
Speed depends on what you are doing. A computer that opens email slowly but plays video smoothly has a different problem than one that freezes during video calls. The fixes are not the same, so start by noticing when the slowness happens — at startup, during specific programs, or all the time.
Most people see improvement by closing programs they are not using, deleting files they do not need, and removing software that came with the computer but serves no purpose. These steps cost nothing and take less time than you think.
Key Takeaways
- Restart your computer first — it clears temporary files and stops background programs that have accumulated since the last restart.
- Check your hard drive space in Settings or System Preferences; if it shows less than 20 percent free, delete old files or move them to an external drive.
- Open your startup programs list and disable anything you do not use daily, because each one slows down boot time and runs in the background.
- Uninstall software you installed but no longer use, especially toolbars, browser extensions, and programs that came with the computer.
- If slowness started suddenly and you cannot find the cause, run a malware scan with Windows Defender (Windows) or Malwarebytes (Mac or Windows).
Restart your computer and check what is running
The first step is always a restart. When a computer runs for weeks without shutting down, temporary files pile up, programs stay open in memory even after you close them, and background tasks accumulate. A restart clears all of that.
After restarting, open your Task Manager (Windows) or Activity Monitor (Mac) to see what is actually running. On Windows, press Ctrl+Shift+Esc. On Mac, press Command+Space, type "Activity Monitor," and press Enter. Look at the CPU and Memory columns — anything using more than 10 to 15 percent of either one is worth investigating.
If you see a program you do not recognize, search its name online before closing it. Some legitimate programs have names that sound suspicious. If you are certain you do not need it, close it. If it restarts itself, it is set to run at startup and you should disable it there instead.
Free up hard drive space
A hard drive that is more than 80 percent full slows down noticeably because the drive has less room to write temporary files. Check how much space you have left by opening Settings (Windows) or System Preferences (Mac) and looking at storage.
Start by deleting files you genuinely do not need: old downloads, duplicate photos, videos you have already backed up, and temporary files. On Windows, use Disk Cleanup (search for it in the Start menu). On Mac, go to About This Mac, click Storage, and look at the recommendations listed there.
If you have large files you want to keep, move them to an external hard drive or cloud storage like Google Drive or OneDrive. This frees up space without losing anything. Once you have at least 20 percent of your drive free, you should notice a difference in speed.
Disable programs that run at startup
Every program set to run at startup adds seconds to boot time and uses memory while your computer is on, even if you never open it. Most computers come with dozens of these, and many are not necessary.
On Windows, press Ctrl+Shift+Esc to open Task Manager, click the Startup tab, and look at the list. Right-click anything you do not use daily and select Disable. Common culprits are Adobe Reader, Spotify, Dropbox, and various manufacturer utilities. On Mac, go to System Preferences, click General, then click Login Items, and remove anything you do not need.
Be cautious: do not disable anything related to security, antivirus, or your keyboard and mouse drivers. If you are unsure, search the program name online first. You can always re-enable it later if you need it.
Uninstall software you do not use
Bloatware — software that came with your computer or that you installed once and forgot about — takes up space and sometimes runs in the background. Uninstalling it is faster than trying to disable every piece of it.
On Windows, go to Settings, click Apps, then Apps and Features, and scroll through the list. Click anything you do not recognize or do not use, then click Uninstall. On Mac, open Applications, drag unused programs to the Trash, and empty the Trash. Pay special attention to toolbars, browser extensions, and utility programs that promise to "speed up" your computer — most of these actually slow it down.
After uninstalling, restart your computer. You may notice boot time improves when ready.
Check for malware and unwanted software
If your computer slowed down suddenly and you have not installed anything new, malware or unwanted software may be the cause. This is different from a virus — it is usually advertising software or browser hijackers that came bundled with something you installed.
Run a scan with Windows Defender (built into Windows) or Malwarebytes (free version available for Mac and Windows). On Windows, open Windows Security, click Virus and Threat Protection, and click Scan Options, then Full Scan. On Mac, read Malwarebytes from their website, install it, and run a full scan. Both are free and take 20 to 40 minutes.
If malware is found, the program will remove it. After removal, restart your computer and check if speed has improved. If slowness continues and you cannot find the cause, the hard drive itself may be failing.
When to replace your hard drive
If your computer is still slow after you have restarted, freed up space, disabled startup programs, and run a malware scan, the hard drive may be failing. Signs include freezing for several seconds at a time, clicking or grinding sounds, or a message saying the drive needs to be repaired.
You cannot fix a failing drive — you have to replace it. This is a job for a repair shop unless you are comfortable opening your computer. Costs vary, but expect to pay between $100 and $300 for parts and labor. A new solid-state drive (SSD) is faster than the original hard drive and will make your computer noticeably quicker overall.
If your computer is more than five years old and the drive is failing, this is a good time to consider whether replacement makes sense compared to buying a new computer.
Frequently Asked Questions
Will clearing my browser cache and cookies speed up my computer?
It will free up a small amount of space and may speed up your browser slightly, but it will not affect overall computer speed. Clear your browser cache if you are having trouble with a specific website, but do not expect it to be a major fix. On Chrome, Firefox, or Edge, press Ctrl+Shift+Delete (Windows) or Command+Shift+Delete (Mac), select All Time, and click Clear Data.
Do I need to buy a cleaning or optimization program?
No. Windows and Mac both include built-in tools that do everything a paid program does. Paid "cleaner" programs often cause more problems than they solve by deleting files they should not touch. Stick with the built-in options: Disk Cleanup on Windows and Storage recommendations on Mac.
Will adding more RAM make my computer faster?
It can, but only if your computer is actually running out of memory. Check Activity Monitor (Mac) or Task Manager (Windows) while using your computer normally. If Memory or RAM usage regularly hits 80 percent or higher, more RAM would help. If it stays below 60 percent, adding RAM will not make a noticeable difference.
How often should I restart my computer?
Once a week is a good habit. If you notice slowness building up, restart sooner. Restarting clears temporary files and stops background processes from accumulating, which is why a fresh restart often feels like an when ready speed boost.
What if my computer is still slow after trying all of this?
The hard drive may be failing, or the computer may straightforward be old enough that its components are wearing out. Run a hard drive diagnostic tool (Windows includes one; search for "Check Disk") to see if the drive is healthy. If the drive is fine and the computer is more than five years old, replacement may be more practical than repair.